Network reselection by a wireless communication device based on signal-to-noise ratio

ABSTRACT

A method for network reselection by a wireless communication device is provided. The wireless communication device can have an established connection to a first network. The method can include measuring a signal strength and a signal-to-noise ratio of the first network. The method can further include determining that the signal strength satisfies a signal strength threshold. The method can additionally include comparing the signal-to-noise ratio to a signal-to-noise ratio threshold. The method can also include disconnecting from the first network and reselecting to a second network in an instance in which the signal-to-noise ratio does not satisfy the signal-to-noise ratio threshold even though the signal strength satisfies the signal strength threshold.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/923,604 filed on Jun. 21, 2013, which claims the benefit of U.S.Provisional Patent Application No. 61/663,492, filed on Jun. 22, 2012,which are incorporated by reference herein in their entirety for allpurposes.

FIELD

The described embodiments relate generally to wireless communicationsand more particularly to network reselection by a wireless communicationdevice based on signal-to-noise ratio.

BACKGROUND

Wireless cellular networks using newer radio access technology (RAT)systems, such as Long Term Evolution (LTE) (including LTE-Advanced)systems, are being developed and deployed. Networks using these newerRATs often support faster theoretical data rates than networks utilizinglegacy RATs, such as second generation (2G) and third generation (3G)RATs, including Universal Mobile Telecommunications System (UMTS)networks and Global System for Mobile Communications (GSM) networks. Insome deployments, however, LTE and other new RATs may not fully supportsome services that can be handled by legacy networks. Accordingly, LTEnetworks and other wireless cellular networks that use newer RATtechnology are often co-deployed in overlapping regions with legacynetworks, and wireless communication devices may transition betweenusing different RATs as services or coverage may require. For example,in some deployments, some LTE networks are not capable of supportingvoice connections. Accordingly, when a wireless communication devicereceives or initiates a voice connection while connected to a networkthat supports data sessions, but not voice connections, the wirelesscommunication device can perform a circuit switched fallback (CSFB)procedure to transition to a legacy network that supports voiceconnections. After completion of a voice connection, the wirelesscommunication device can transition back to the LTE network to enjoyfaster data rates.

In some instances, a wireless communication device can reselect from anLTE network to a legacy network even if a voice connection is notinitiated. For example, a signal strength (e.g., a measure of a receivedsignal power) of the LTE network at the wireless communication devicecan degrade to a level below a network-configured reselection threshold,and the wireless communication device can reselect to a legacy networkoffering a better signal strength. In some circumstances, however,signal strength alone may not suffice to determine whether channelquality can adequately support communication with a particular wirelesscommunication device or for particular wireless services, and a wirelesscommunication device can remain on an LTE network even in situations inwhich it is desirable to reselect to a legacy network. In this regard,while a measured signal strength of a signal from a serving LTE basestation can indicate sufficient signal power for satisfactorycommunication, additional signals emitted by other neighboring LTEcells, by proximate wireless communication devices, and/or by basestations of neighboring legacy networks can result in significantsignaling interference at a wireless communication device, particularlyat an edge of an LTE cell. The increased interference can negativelyimpact signal quality at the wireless communication device and canimpede clear reception of signaling messages from the serving LTEnetwork, even in instances in which the serving LTE network's signalstrength satisfies a signal strength threshold.

SUMMARY

Some embodiments disclosed herein provide for network reselection by awireless communication device based on signal-to-noise ratio. In thisregard, a wireless communication device in accordance with some exampleembodiments can be configured to measure a signal-to-noise ratio of afirst network to which the wireless communication device can have anestablished connection. The wireless communication device of suchexample embodiments can be configured to compare the measuredsignal-to-noise ratio to a signal-to-noise ratio threshold, and canreselect to a second network in an instance in which the measuredsignal-to-noise ratio does not satisfy a signal-to-noise ratiothreshold, even in instances in which a measured signal strength of thefirst network satisfies a signal strength threshold. Accordingly,reselection to a second network can be performed in areas withrelatively high amounts of interference, even if a measured signalstrength satisfies a network configured threshold. As such, some exampleembodiments can improve reception of data by a wireless communicationdevice by enabling reselection in interference conditions on the basisof a signal-to-noise ratio threshold. In this regard, by preemptivelyreselecting to a different network based on signal-to-noise ratio, awireless communication device can increase the likelihood that incomingdata, such as a signaling message, e.g., for a voice connection, isreceived and decoded successfully.

In a first embodiment, a method for network reselection by a wirelesscommunication device is provided. The method of the first embodiment caninclude measuring a signal strength and a signal-to-noise ratio of afirst network. The wireless communication device can have an establishedconnection to the first network. The method of the first embodiment canfurther include determining that the signal strength satisfies a signalstrength threshold; comparing the signal-to-noise ratio to asignal-to-noise ratio threshold; and disconnecting from the firstnetwork and reselecting to a second network when the signal-to-noiseratio does not satisfy the signal-to-noise ratio threshold and thesignal strength satisfies the signal strength threshold.

In a second embodiment, a wireless communication device is provided. Thewireless communication device of the second embodiment can includewireless circuitry and processing circuitry coupled to the wirelesscircuitry. The wireless circuitry can be configured to transmit data toand receive data from a first network and a second network. Theprocessing circuitry can be configured to control the wirelesscommunication device of the second embodiment to at least establish aconnection to the first network; measure a signal strength and asignal-to-noise ratio of the first network; determine that the signalstrength satisfies a signal strength threshold; compare thesignal-to-noise ratio to a signal-to-noise ratio threshold; anddisconnect from the first network and reselect to the second networkwhen the signal-to-noise ratio does not satisfy the signal-to-noiseratio threshold and the signal strength satisfies the signal strengththreshold.

In a third embodiment, a computer program product for facilitatingnetwork reselection by a wireless communication device is provided. Thecomputer program product of the third embodiment can include at leastone non-transitory computer readable storage medium having program codestored thereon. The program code of the third embodiment can includeprogram code for measuring a signal strength of a first network. Thewireless communication device can have an established connection to thefirst network. The program code of the third embodiment can furtherinclude program code for measuring a signal-to-noise ratio of the firstnetwork; program code for determining that the signal strength satisfiesa signal strength threshold; program code for comparing thesignal-to-noise ratio to a signal-to-noise ratio threshold; and programcode for disconnecting from the first network and reselecting to asecond network when the signal-to-noise ratio does not satisfy thesignal-to-noise ratio threshold and the signal strength satisfies thesignal strength threshold.

In a fourth embodiment, an apparatus is provided. The apparatus of thefourth embodiment can include means for measuring a signal strength anda signal-to-noise ratio of a first network. The apparatus can have anestablished connection to the first network. The apparatus of the fourthembodiment can further include means for determining that the signalstrength satisfies a signal strength threshold; means for comparing thesignal-to-noise ratio to a signal-to-noise ratio threshold; and meansfor disconnecting from the first network and reselecting to a secondnetwork when the signal-to-noise ratio does not satisfy thesignal-to-noise ratio threshold and the signal strength satisfies thesignal strength threshold.

The above summary is provided merely for purposes of summarizing someexample embodiments so as to provide a basic understanding of someaspects of the disclosure. Accordingly, it will be appreciated that theabove described example embodiments are merely examples and should notbe construed to narrow the scope or spirit of the disclosure in any way.Other embodiments, aspects, and advantages will become apparent from thefollowing detailed description taken in conjunction with theaccompanying drawings, which illustrate, by way of example, theprinciples of the described embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The described embodiments and the advantages thereof may best beunderstood by reference to the following description taken inconjunction with the accompanying drawings. These drawings are notnecessarily drawn to scale, and in no way limit any changes in form anddetail that may be made to the described embodiments by one skilled inthe art without departing from the spirit and scope of the describedembodiments.

FIG. 1 illustrates overlapping coverage of a fourth generation (4G)network and a legacy network in accordance with some embodiments.

FIG. 2 is a graph illustrating a relationship between a measuredsignal-to-noise and interference ratio and a page success rate.

FIG. 3 is a graph plotting signal-to-noise versus a cumulativepercentage of occurrence.

FIG. 4 illustrates an example system having multiple wirelesscommunication networks to which a wireless communication device canconnect in accordance with some embodiments.

FIG. 5 illustrates a block diagram of an apparatus that can beimplemented on a wireless communication device in accordance with someembodiments.

FIG. 6 illustrates a flowchart according to a representative method fornetwork reselection by a wireless communication device based onsignal-to-noise ratio in accordance with some embodiments.

FIG. 7 illustrates a flowchart according to another example method fornetwork reselection by a wireless communication device based onsignal-to-noise ratio in accordance with some embodiments.

FIG. 8 illustrates a flowchart according to a further example method fornetwork reselection by a wireless communication device based onsignal-to-noise ratio in accordance with some embodiments.

DETAILED DESCRIPTION

Representative applications of methods and apparatus according to thepresent disclosure are described in this section. These examples arebeing provided solely to add context and aid in the understanding of thedescribed embodiments. It will thus be apparent to one skilled in theart that the described embodiments may be practiced without some or allof these specific details. In other instances, well known process stepshave not been described in detail in order to avoid unnecessarilyobscuring the described embodiments. Other applications are possible,such that the following examples should not be taken as limiting.

In the following detailed description, references are made to theaccompanying drawings, which form a part of the description and in whichare shown, by way of illustration, specific embodiments in accordancewith the described embodiments. Although these embodiments are describedin sufficient detail to enable one skilled in the art to practice thedescribed embodiments, it is understood that these examples are notlimiting; such that other embodiments may be used, and changes may bemade without departing from the spirit and scope of the describedembodiments.

Some embodiments disclosed herein provide for network reselection by awireless communication device based on signal-to-noise ratio. In thisregard, some example embodiments provide for reselection from a firstnetwork to a second network in a mixed environment in which the wirelesscommunication device can be operating in the presence of overlappingcoverage from multiple networks, which can use different radio accesstechnologies (RATs) such that the wireless communication device canreselect to a second network in response to a signal-to-noise ratiomeasured on the first network failing to satisfy a threshold level.Accordingly, reselection can be performed in situations in whichinterference conditions can impede reception of data, such as, by way ofnon-limiting example, incoming paging messages, by the wirelesscommunication device on the first network.

FIG. 1 illustrates overlapping coverage of a fourth generation (4G)network 102 and a legacy network 104 in a communications system 100 inaccordance with some example embodiments. The 4G network 102 can, forexample, be a network implementing an LTE wireless communicationprotocol in accordance with a Third Generation Partnership Project(3GPP) standard, such as an LTE network or an LTE-Advanced (LTE-A)network, or other network that can offer faster data rates than legacynetworks, such as 2G and 3G networks, but may not support voiceconnections. It will be appreciated that the 4G network is illustratedby way of example, and not by way of limitation. In this regard, othernetworks in existence now or that may be developed in the future thatoffer higher data rates but that do not support circuit switched (CS)voice connections can be substituted for the 4G network 102 within thescope of the disclosure. The legacy network 104 can be any legacynetwork having a Circuit switched domain to support CS voiceconnections. By way of non-limiting example, the legacy network 104 canbe a 3G network, such as a Wideband Code Division Multiple Access(WCDMA) or other Universal Mobile Telecommunications System (UMTS)network, such as a Time Division Synchronous Code Division MultipleAccess (TD-SCDMA) network. As a further example, the legacy network 104can be a CDMA2000 network, such as a 1xRTT network, or other networkstandardized by the Third Generation Partnership Project 2 (3GPP2) thatsupports a Circuit switched domain. As another example, the legacynetwork can be a 2G network such as a Global System for MobileCommunications (GSM) network.

The 4G network 102 and legacy network 104 can each have regions ofcoverage represented by the respective circles illustrated in FIG. 1.The regions of coverage can overlap, such as illustrated by theoverlapping portions of the circles in FIG. 1. A wireless communicationdevice in accordance with some example embodiments can operate on boththe 4G network 102 and the legacy network 104. Thus, for example, when awireless communication device is in a region of overlapping coveragefrom both the 4G network 102 and the legacy network 104, the wirelesscommunication device can establish a connection to either the 4G network102 or the legacy network 104.

When a wireless communication device is camped on the 4G network 102,reselection to the legacy network 104 can be governed by a referencesignal receive power (RSRP) level. A value for the RSRP level canprovide information regarding an amount of signal strength received bythe wireless communication device at a particular location. Using theRSRP value as a measure of signal strength, the 4G network 102 can set athreshold level to guide the wireless communication device when to leavethe 4G network 102 and reselect to the legacy network 104. In someexample embodiments, the 4G network 102 can set the threshold to a levelat which a reselection process can be initiated at around −104 dBm.Alternatively, in some embodiments, the 4G network 102 can set thethreshold to −110 dBm. If a measured RSRP value is less than thethreshold, the 4G network 102 can signal the wireless communicationdevice to leave the 4G network 102, and reselect to the legacy network104. A mobile network operator can prefer to keep a wirelesscommunication device on the 4G network 102, which can provide higherdata rates, over a legacy network 104, and thus can set a threshold to alevel at which reselection from the 4G network 102 to the legacy network104 requires a low signal strength. Signal strength alone, however, maynot adequately determine performance for a wireless communicationdevice, as added noise and interference can affect the wirelesscommunication device's ability to properly receive and decode messages,including critical signaling messages.

Making reselection decisions to switch from a 4G network 102 to a legacynetwork 104, or the reverse, determined solely on measurement of areceived signal strength, e.g., the RSRP, can lead to poor operatingconditions for a wireless communication device. Poor operatingconditions at the wireless communication device can arise frominterfering signals emitted by nearby wireless access points or otherwireless devices that can operate in a frequency band overlapping,adjacent to, and/or near a current operating frequency band of thewireless communication device. FIG. 2 illustrates a graph 200 ameasurement of a signal-to-noise ratio (more specifically, a referencesignal signal-to-interference-and-noise ratio (RS-SINR)) on the X-axisand a page success rate on the Y-axis. A page is a signaling messagesent by the network to the wireless communication device to provideinformation for control of connections between the wirelesscommunication device and one or more networks. For example, a page canindicate a proposed connection, e.g., an incoming voice connection. Insome instances, a page can be signaled to a wireless communicationdevice camped on a 4G network to indicate the presence of an incoming CSvoice connection for which the wireless communication device can berequired to perform a CSFB procedure in order to transition from the 4Gnetwork to a legacy network for receiving the voice connection on aCircuit switched domain of the legacy network. As the graph 200 of FIG.2 illustrates, as the level of interference increases (resulting inlower SINR) at the wireless communication device, the probability thatthe wireless communication device successfully receives a paging messagedecreases, which can result in the wireless communication device missingan incoming voice connection request. As the RS-SINR drops below a levelof approximately 0 dB, the page performance success rate steadilydecreases, e.g., at an RS-SINR less than 3 dB, the page success rate ofthe wireless communication device successfully decoding a paging messagecan be less than 50%.

FIG. 3 illustrates a graph 300 that plots a measured signal-to-noiseratio versus a cumulative percentage of occurrence in a number ofnetworks. The graph of FIG. 3 illustrates a relationship of a measuredsignal-to-noise ratio (i.e., a representative signal quality metric) ata wireless communication device to cumulative distribution function(CDF) of the probability of occurrence of the SNR, particularly in anurban environment, for a representative set of field measurements in anumber of different wireless networks. Decreasing values of thesignal-to-noise ratio are plotted on the X-axis. The graph of FIG. 3shows that a wireless communication device can measure a relatively lowSNR value, e.g. 0 dB or less, in approximately 10% of the measurementoccurrences. Unfortunately, interference levels at the wirelesscommunication device are not indicated in signal strength, e.g., RSRP,measurements, and reselection decisions based only on measurements ofRSRP can result in a wireless communication device continuing to operatein conditions of low SNR that can cause the wireless communicationdevice to not receive correctly one or more signaling messages, and thusto potentially miss paging messages for establishing a voice connection.As such, some example embodiments provide for reselection on the basisof a measured signal-to-noise ratio that includes measuringinterference, noise, and/or signal quality in addition to measuringsignal strength at a wireless communication device.

FIG. 4 illustrates an example wireless network system 400 includingmultiple wireless communication networks 404/406 to which a wirelesscommunication device 402 can connect in accordance with some exampleembodiments. By way of non-limiting example, the wireless communicationdevice 402 can be a cellular phone, such as a smart phone device; atablet computing device; a laptop computing device; or other computingdevice configured to operate within both a first network 404 and alegacy network 406. In some example embodiments, such as embodiments inwhich the wireless communication device 402 is configured to connect toa network implementing an LTE standard, the wireless communicationdevice 402 can be embodied as user equipment (UE). The first network 404can, for example, be a network supporting packet switched (PS) datasessions, offering higher theoretical data rates than the legacy network406, but not supporting CS voice connections. Thus, for example, thefirst network 404 can be a network implementing a version of an LTEstandard (e.g., an LTE network, LTE-A network, or using another presentor future developed LTE standard) or other 4G network, such as the 4Gnetwork 102 illustrated in FIG. 1. The legacy network 406 can, forexample, be a network that includes a Circuit switched domain to supportCS voice connections. By way of non-limiting example, the legacy network406 can be a UMTS network, a network based on a 3GPP2 wirelesscommunication protocol, or another 3G network. As a further example, thelegacy network 406 can be a GSM or other 2G network, or other legacynetwork that can support CS voice connections. In this regard, thelegacy network 406 can be the legacy network 104.

As illustrated in FIG. 4, the wireless communication device 402 can bewithin signaling range of both a base station or other access networkequipment for the first network 404 and a base station or other accessnetwork equipment for the legacy network 406. In this regard, thewireless communication device 402 can be located in a region ofoverlapping coverage of the first network 404 and the legacy network406. As such, the wireless communication device 402 can be connected tothe first network 404, and can reselect to the legacy network 406.

FIG. 5 illustrates a block diagram of an apparatus 500 that can beimplemented on a wireless communication device 402 in accordance withsome example embodiments. In this regard, when implemented on acomputing device, such as wireless communication device 402, apparatus500 can enable the computing device to operate within the system 400 inaccordance with one or more example embodiments. It will be appreciatedthat the components, devices or elements illustrated in and describedwith respect to FIG. 5 below may not be mandatory and thus some may beomitted in certain embodiments. Additionally, some embodiments caninclude further or different components, devices or elements beyondthose illustrated in and described with respect to FIG. 5.

In some example embodiments, the apparatus 500 can include processingcircuitry 510 that is configurable to perform actions in accordance withone or more example embodiments disclosed herein. In this regard, theprocessing circuitry 510 can be configured to perform and/or controlperformance of one or more functionalities of the apparatus 500 inaccordance with various example embodiments, and thus can provide meansfor performing functionalities of the apparatus 500 in accordance withvarious example embodiments. The processing circuitry 510 can beconfigured to perform data processing, application execution and/orother processing and management services according to one or moreexample embodiments.

In some embodiments, the apparatus 500 or a portion(s) or component(s)thereof, such as the processing circuitry 510, can include one or morechipsets, which can each include one or more chips. The processingcircuitry 510 and/or one or more further components of the apparatus 500can therefore, in some instances, be configured to implement anembodiment on a chipset including one or more chips. In some exampleembodiments in which one or more components of the apparatus 500 areembodied as a chipset, the chipset can be capable of enabling acomputing device to operate in the system 400 when implemented on orotherwise operably coupled to the computing device. Thus, for example,one or more components of the apparatus 500 can provide a chipsetconfigured to enable a computing device to operate over the firstnetwork 404 and/or the legacy network 406.

In some example embodiments, the processing circuitry 510 can include aprocessor 512 and, in some embodiments, such as that illustrated in FIG.5, can further include memory 514. The processing circuitry 510 can bein communication with or otherwise control wireless circuitry 516 and/orthe selection control module 518.

The processor 512 can be embodied in a variety of forms. For example,the processor 512 can be embodied as various processing means such as amicroprocessor, a coprocessor, a controller or various other computingor processing devices including integrated circuits such as, forexample, an ASIC (application specific integrated circuit), an FPGA(field programmable gate array), some combination thereof, or the like.Although illustrated as a single processor, it will be appreciated thatthe processor 512 can comprise a plurality of processors. The pluralityof processors can be in operative communication with each other and canbe collectively configured to perform one or more functionalities of theapparatus 500 as described herein. In some example embodiments, theprocessor 512 can be configured to execute instructions that can bestored in the memory 514 or that can be otherwise accessible to theprocessor 512. As such, whether configured by hardware or by acombination of hardware and software, the processor 512 can be capableof performing operations according to various embodiments whileconfigured accordingly.

In some example embodiments, the memory 514 can include one or morememory devices. Memory 514 can include fixed and/or removable memorydevices. In some embodiments, the memory 514 can provide anon-transitory computer-readable storage medium that can store computerprogram instructions that can be executed by the processor 512. In thisregard, the memory 514 can be configured to store information, data,applications, instructions and/or the like for enabling the apparatus500 to carry out various functions in accordance with one or moreexample embodiments. In some embodiments, the memory 514 can be incommunication with one or more of the processor 512, wireless circuitry516, or selection control module 518 via a bus(es) for passinginformation among components of the apparatus 500.

The apparatus 500 can further include wireless circuitry 516. Thewireless circuitry 516 can enable the apparatus 500 to send wirelesssignals to and receive signals from one or more wireless networks, suchas the first network 404 and the legacy network 406. In someembodiments, the wireless circuitry 516 can include components such as:processors and/or specific-purpose DSP circuitry for implementingfunctionality such as, but not limited to, baseband signal processing,physical layer processing, data link layer processing, and/or otherfunctionality; one or more digital to analog converters (DACs) forconverting digital data to analog signals; one or more analog to digitalconverters (ADCs) for converting analog signals to digital data; radiofrequency (RF) circuitry (e.g., one or more amplifiers, mixers, filters,phase lock loops (PLLs), and/or oscillators); and/or other components.As such, the wireless circuitry 516 can be configured to support anytype of cellular or other wireless communication technology that may beimplemented by the first network 404 and/or legacy network 406. In someexample embodiments, the wireless circuitry 516 can be configured toenable the wireless communication device 402 to connect to both thefirst network 404 and the legacy network 406, e.g., using a “combined”wireless chipset that supports wireless communication protocols for thefirst network 404 and the legacy network 406. Alternatively, in someexample embodiments, the wireless circuitry 516 can include a firstwireless communication block configured to enable the wirelesscommunication device 402 to connect to the first network 404 and asecond separate wireless communication block configured to enable thewireless communication device 402 to connect to the legacy network 406.

The apparatus 500 can further include selection control module 518. Theselection control module 518 can be embodied as various means, such ascircuitry, hardware, a computer program product comprising computerreadable program instructions stored on a computer readable medium (forexample, the memory 514) and executed by a processing device (forexample, the processor 512), or some combination thereof. In someembodiments, the processor 512 (or the processing circuitry 510) caninclude, or otherwise control the selection control module 518.

The selection control module 518 can be configured in some exampleembodiments to measure characteristics of the first network 404 whilethe wireless connection device 402 is connected to the first network404. The measured characteristics can include a measured signal strengthof the first network 404. In some example embodiments, such as someembodiments in which the first network 404 implements an LTE standard,the measured signal strength can be a measured RSRP of the first network404. The measured characteristics can further include a measuredsignal-to-noise ratio (SNR) of the first network 404. In some exampleembodiments, the measured SNR can factor in interference and noise, andcan be defined as a signal-to-interference-and-noise ratio (SINR). Forexample, in some embodiments, such as some embodiments in which thefirst network 404 implements an LTE standard, the measured SNR can be ameasured reference signal-SINR (RS-SINR) of the first network 404.

The wireless communication device 402 can be provided with a signalstrength threshold value, e.g., based on measurements of a signal sentby the first network 404 and received by the wireless communicationdevice 402, such as an RSRP threshold. The first network 404 can, forexample, define the signal strength threshold. In various exampleembodiments, the signal strength threshold can, by way of non-limitingexample, be set by the first network 404 to a value of −104 dBm or avalue of −110 dBm (or other similar signal strength measurement valuesthat can correspond to relatively low signal strength in a particularnetwork). If the measured signal strength fails to satisfy a signalstrength condition, (e.g., is less than; or less than or equal to), forthe signal strength threshold, then reselection by the wirelesscommunication device 402 from the first network 402 to the legacynetwork 406 can occur.

In accordance with some example embodiments, an SNR threshold can bedefined in addition to the signal strength threshold. For example, inembodiments in which an RS-SINR is measured for the first network 404,the SNR threshold can be an SNR threshold. The selection control module518 can be configured in some example embodiments to compare a measuredSNR of the first network 404 to the SNR threshold, and if the measuredSNR fails to satisfy the SNR threshold, the selection control module 418can initiate reselection from the first network 404 to the legacynetwork 406. For example, if the measured SNR is less than (or less thanor equal to, depending on how the threshold is configured) the SNRthreshold, the selection control module 518 can be configured to triggera reselection from the first network 404 to the legacy network 406.Accordingly, even if a measured signal strength of the first network 404satisfies a signal strength condition based on a measure of a signalstrength compared to a signal strength threshold value, reselection fromthe first network 404 to the legacy network 406 can be performed ininterference scenarios on the basis of a measured SNR of the firstnetwork 404.

In some example embodiments, the wireless communication device 402 candefine the SNR threshold. The SNR threshold can be defined as a valuefor an SNR at which data, e.g., signaling messages, received from anetwork, e.g., the first network 404, can be successfully decoded. Forexample, the SNR can be defined as an SNR at which a paging message,such as for establishing a CS voice connection, can be successfullyreceived and decoded by the wireless communication device 402. By way ofnon-limiting example, the SNR threshold can be set to a value on theorder of −3 dB, in some example embodiments. In some embodiments, theSNR threshold can correspond to a value that triggers a reselectionsearch for a new network and/or cell of a network with which toassociate. In some embodiments, a second SNR threshold value (or a rangeof values) can be used to determine after a portion of the reselectionprocess whether to remain on the first network 404 or reselect to anewly found network, e.g., the legacy network 406. Thus, a first SNRthreshold can result in triggering a search for a “better” network, andfollowing an evaluation of available network cells, the wirelesscommunication device 402 can re-check a current value of SNR todetermine whether to switch to one of the located network cells.

The SNR threshold can, for example, be a static threshold. In someembodiments, the network can establish a value for the SNR threshold,e.g., through a signaling message. Alternatively, in some exampleembodiments, the SNR threshold can be adjusted based on historicaland/or current operating conditions seen by the wireless communicationdevice 402. For example, in some example embodiments, the SNR thresholdcan be determined by the selection control module 518 of the wirelesscommunication device 402 based at least in part on historical data thattracks paging messages previously missed by the wireless communicationdevice 402. In this regard, the selection control module 518 can beconfigured in such example embodiments to gather data regarding missedpages and measurements of SNR (e.g., RS-SINR) over a period of time(e.g., the past hour, day, month, or other period), and can determine anappropriate SNR threshold value on the basis of the measured and/ortracked historical data. In some example embodiments, the SNR thresholdcan be determined further based on a location of the wirelesscommunication device 402. In this regard, missed pages can be correlatedwith location information in order to define location-specificthresholds. For example, the selection control module 518 can beconfigured to determine an approximate and/or an exact location throughuse of network-provided information, a positioning sensor, such as aGlobal Positioning System (GPS) sensor, location available from a Wi-Ficonnection, a cell identifier, and/or other indication of location, andcan associate historical data for successful/failed pages andcorresponding SNR with the location. In some such example embodiments, alocation can encompass a geographic region.

In some example embodiments, the selection control module 518 can beconfigured to measure a channel quality of the legacy network 406. Themeasured channel quality of the legacy network 406 can, for example,include a measure of signal strength, such as a received signal codepower (RSCP), of the legacy network 406. Additionally or alternatively,the measured channel quality can include an SNR of the legacy network406, such as an energy per chip/interference (Ec/Io) of the legacynetwork 406. The selection control module 518 can be configured, in somesuch embodiments, to use the measured channel quality of the legacynetwork 406 to verify that the channel quality of the legacy network 406satisfies a channel quality threshold prior to reselecting from thefirst network 404 to the legacy network 406. In this regard, forexample, the measured channel quality can be used to ensure that thechannel quality of the legacy network 406 is better than that of thefirst network 404. If the channel quality of the legacy network 406 doesnot satisfy a channel quality metric, the selection control module 518,in some embodiments, can remain on the first network 404 even when themeasured SNR of the first network 404 does not satisfy the SNRthreshold.

FIG. 6 illustrates a flowchart according to an example method fornetwork reselection by a wireless communication device, e.g., thewireless communication device 402, based on signal-to-noise ratioaccording to some example embodiments. Operation 600 can includemeasuring a signal strength and an SNR of a first network, such as thefirst network 404. The measured signal strength can, for example, be ameasured RSRP of a serving cell of the first network. The measured SNRcan, for example, be a measured SINR, such as an RS-SINR of the servicecell of the first network. Operation 610 can include determining thatthe measured signal strength satisfies a signal strength threshold,e.g., having a measured value that equals or exceeds an RSRP thresholdvalue set by the first network. Operation 620 can include comparing themeasured SNR to an SNR threshold and determining whether the measuredSNR satisfies the SNR threshold. If it is determined at operation 620that the measured SNR satisfies the SNR threshold, e.g., a value of ameasured signal-to-noise/interference ratio equals or exceeds an RS-SINRthreshold value set by the wireless communication device 402, the methodcan proceed to operation 630, which can include determining to remain onthe first network. If, however, it is determined at operation 620 thatthe measured SNR does not satisfy the SNR threshold, e.g., the measuredSNR does not equal or exceeds the RS-SINR threshold value set by thewireless communication device 402, the method can proceed to operation640, which can include the wireless communication device disconnectingfrom the first network and reselecting to a second network, such as thelegacy network 406. In this regard, the wireless communication device402 can determine to reselect to the second network and initiate thereselection in response to the measured SNR failing to satisfy the SNRthreshold. In some embodiments, the wireless communication device 402can satisfy a network signal strength condition but can also fail asignal quality (e.g., SNR) condition set by the wireless communicationdevice, and therefore based on poor measured signal quality (despitesatisfactory measured signal strength), the mobile wirelesscommunication device 402 can initiate a reselection procedure. One ormore of the processing circuitry 510, processor 512, memory 514,transceiver(s) 516, or selection control module 518 can, for example,provide means for performing operations 610-640.

FIG. 7 illustrates a flowchart according to another example method fornetwork reselection by a wireless communication device, e.g., thewireless communication device 402, based on measurement of asignal-to-noise ratio according to some example embodiments. One or moreof the processing circuitry 510, processor 512, memory 514, wirelesscircuitry 516, or selection control module 518 can, for example, providemeans for performing the operations illustrated in and described withrespect to FIG. 7. Operation 700 can include measuring a signal strengthand an SNR of a first network, such as the first network 404. Themeasured signal strength can, for example, be a measured RSRP of thefirst network. The measured SNR can, for example, be a measured SINR,such as an RS-SINR of the first network. Operation 710 can includedetermining whether the measured signal strength satisfies a signalstrength threshold. The signal strength threshold can, for example, bedefined by the first network. If it is determined at operation 710 thatthe measured signal strength satisfies the signal strength threshold,the method can proceed to operation 720, which can include determiningwhether the measured SNR satisfies an SNR threshold. If it is determinedat operation 720 that the measured SNR satisfies the SNR threshold, themethod can, for example, return to operation 710 (or alternativelyoperation 700).

If, however, it is determined at operation 720 that the measured SNRdoes not satisfy the SNR threshold, the method can proceed to operation730, which can include determining whether a channel quality of a secondnetwork, such as the legacy network 406, satisfies a channel qualitythreshold. If it is determined at operation 730 that the channel qualityof the second network satisfies the channel quality threshold, themethod can proceed to operation 740, which can include the wirelesscommunication device 402 reselecting to the second network. Reselectingto the second network can include the wireless communication device 402disconnecting from the first network and connecting to the secondnetwork. In this regard, the wireless communication device 402 candetermine to reselect to the second network and initiate the reselectionin response to the measured SNR failing to satisfy the SNR threshold.

If, on the other hand, it is determined at operation 730 that thechannel quality of the second network does not satisfy the channelquality threshold, the wireless communication device 402 can remain onthe first network. The method can, for example, return to operation 710(or alternatively operation 700).

In an instance in which it is determined at operation 710 that themeasured signal strength does not satisfy the signal strength threshold,the method can proceed to operation 750, and operation 720 can beomitted. Operation 750 can include triggering reselection to the secondnetwork based on the measured signal strength. The method canaccordingly proceed to operation 730 and/or operation 740.

FIG. 8 illustrates a flowchart according to a further example method fornetwork reselection by a wireless communication device based onmeasurement of a signal-to-noise ratio according to some exampleembodiments. One or more of the processing circuitry 510, processor 512,memory 514, transceiver(s) 516, or selection control module 518 can, forexample, provide means for performing the operations illustrated in anddescribed with respect to FIG. 8. The method can begin with operation800, in which the wireless communication device 402 can be camped on anLTE network. Operation 810 can include measuring an RS-SINR and RSRP ofthe LTE network. Operation 810 can further include measuring an Echo andRSCP of a legacy network.

Operation 820 can include comparing the measured RSRP to an RSRPthreshold to determine if the measured RSRP satisfies the RSRPthreshold. The RSRP threshold can be set by the LTE network in someexample embodiments. If the measured RSRP does not satisfy the RSRPthreshold, the method can proceed to operation 830, which can includetriggering a reselection to the legacy network based on the measuredRSRP. Operation 840 can include determining whether a channel quality ofthe legacy network satisfies a channel quality threshold. Thedetermination of operation 840 can, for example, be based on themeasured Echo and/or RSCP of the legacy network, such as can be measuredat operation 810. The determination of operation 840 can, for example,be performed in accordance with one or more LTE specifications orguidelines, e.g., based on an LTE network reselection quality criterion,and/or based on a legacy network specification, guideline, or othercriteria established for reselection from one network to another. If thechannel quality of the legacy network is determined to satisfy thechannel quality threshold (e.g., good legacy network channel quality),the method can proceed to operation 850, which can include the wirelesscommunication device 402 reselecting to the legacy network. If, however,it is determined that the channel quality of the legacy network does notsatisfy the channel quality threshold (e.g., poor legacy network channelquality), the wireless communication device 402 can remain on the LTEnetwork in spite of the measured RSRP not satisfying the RSRP threshold.The method can, for example return to operation 820 (or alternativelyoperation 810).

If, on the other hand, it is determined at operation 820 that themeasured RSRP of the LTE network satisfies the RSRP threshold, themethod can proceed to operation 860, which can include determiningwhether the measured RS-SINR of the LTE network satisfies a RS-SINRthreshold. In some example embodiments, the RS-SINR threshold can bedefined by the wireless communication device 402. The RS-SINR thresholdcan, for example, be a static threshold, or can be adjusted based onpast and/or current operating conditions seen by the wirelesscommunication device 402. For example, the RS-SINR threshold can bedetermined based at least in part on historical data regarding missedpages and corresponding RS-SINR. In some example embodiments, theRS-SINR threshold can be determined further based on a location of thewireless communication device 402. In this regard, in some such exampleembodiments, missed pages can be correlated with location information,such as can be determined from the network, GPS data, location dataavailable through Wi-Fi connections, and/or the like, and one or morelocation-specific SINR thresholds can be defined.

If the measured RS-SINR does not satisfy the RS-SINR threshold, then thecurrent serving cell may not provide adequate performance, and incomingpages can be missed. As such, if it is determined at operation 860 thatthe measured RS-SINR does not satisfy the SINR threshold, a reselectionprocess can be triggered by the wireless communication device 402, andthe method can proceed to operation 840. If, however, it is determinedat operation 860 that the measured RS-SINR does satisfy the SINRthreshold, the wireless communication device 402 can remain on the LTEnetwork. The method can, for example return to operation 820 (oralternatively operation 810).

The various aspects, embodiments, implementations or features of thedescribed embodiments can be used separately or in any combination.Various aspects of the described embodiments can be implemented bysoftware, hardware or a combination of hardware and software. Thedescribed embodiments can also be embodied as computer readable code ona computer readable medium. The computer readable medium is any datastorage device that can store data which can thereafter be read by acomputer system. Examples of the computer readable medium includeread-only memory, random-access memory, CD-ROMs, HDDs, DVDs, magnetictape, and optical data storage devices. The computer readable medium canalso be distributed over network-coupled computer systems so that thecomputer readable code is stored and executed in a distributed fashion.

The foregoing description, for purposes of explanation, used specificnomenclature to provide a thorough understanding of the describedembodiments. However, it will be apparent to one skilled in the art thatthe specific details are not required in order to practice the describedembodiments. Thus, the foregoing descriptions of specific embodimentsare presented for purposes of illustration and description. They are notintended to be exhaustive or to limit the described embodiments to theprecise forms disclosed. It will be apparent to one of ordinary skill inthe art that many modifications and variations are possible in view ofthe above teachings.

What is claimed is:
 1. A method for network reselection by a wirelesscommunication device, the method comprising: measuring a downlink signalstrength and a downlink signal quality of a first network to which thewireless communication device has an established connection; determiningwhether the downlink signal strength satisfies a downlink signalstrength threshold; disconnecting from the first network and reselectingto a second network, when the downlink signal strength threshold is notsatisfied; and when the downlink signal strength satisfies the downlinksignal strength threshold: determining whether the downlink signalquality satisfies a downlink signal quality threshold, and disconnectingfrom the first network and reselecting to the second network when thedownlink signal quality does not satisfy the downlink signal qualitythreshold.
 2. The method of claim 1, wherein the downlink signalstrength comprises a reference signal received power (RSRP) and thedownlink signal strength threshold comprises an RSRP thresholddetermined by the first network.
 3. The method of claim 1, wherein thedownlink signal quality comprises a downlinksignal-to-interference-plus-noise-ratio (SINR) and the downlink signalquality threshold comprises a downlink SINR threshold determined by thewireless communication device.
 4. The method of claim 3, wherein thedownlink SINR threshold comprises an SINR sufficient to enablesuccessful decoding of a paging message received from the first network.5. The method of claim 3, wherein the downlink SINR threshold isdetermined based at least in part on historical data of one or morepaging messages previously missed by the wireless communication device.6. The method of claim 5, wherein the downlink SNR threshold isdetermined further based on a location of the wireless communicationdevice.
 7. The method of claim 1, further comprising: measuring achannel quality of the second network before reselecting to the secondnetwork; and wherein reselecting to the second network comprisesreselecting to the second network when the channel quality of the secondnetwork satisfies a channel quality threshold, and wherein the methodfurther comprises remaining on the first network when the channelquality of the second network does not satisfy the channel qualitythreshold.
 8. The method of claim 7, wherein the channel quality of thesecond network comprises one or more of a signal energy to interferenceratio (Echo) and a received signal code power (RSCP).
 9. The method ofclaim 7, wherein the channel quality threshold comprises a threshold forreselection or handover specified by the first network and/or the secondnetwork.
 10. The method of claim 1, wherein the first network comprisesan LTE wireless network that operates in accordance with at least one ofa version of a Third Generation Partnership Project (3GPP) LTE orLTE-Advanced (LTE-A) wireless communication protocol, and wherein thesecond network comprises one of a Wideband Code Division Multiple Access(WCDMA) network, a Universal Mobile Telecommunications System (UMTS)network, a Global System for Mobile Communications (GSM) network, or anetwork operating in accordance with a wireless communication protocolof the Third Generation Partnership Project 2 (3GPP2).
 11. A wirelesscommunication device comprising: wireless circuitry configured totransmit data to and receive data from a first network and a secondnetwork; and processing circuitry coupled to the wireless circuitry, theprocessing circuitry configured to cause the wireless communicationdevice to: measure a downlink signal strength and a downlink signalquality of a first network to which the wireless communication devicehas an established connection; determine whether the downlink signalstrength satisfies a downlink signal strength threshold; disconnect fromthe first network and reselect to a second network, when the downlinksignal strength threshold is not satisfied; and when the downlink signalstrength satisfies the downlink signal strength threshold: determinewhether the downlink signal quality satisfies a downlink signal qualitythreshold, and disconnect from the first network and reselect to thesecond network when the downlink signal quality does not satisfy thedownlink signal quality threshold.
 12. The wireless communication deviceof claim 11, wherein the downlink signal strength comprises a referencesignal received power (RSRP) and the downlink signal strength thresholdcomprises an RSRP threshold determined by the first network.
 13. Thewireless communication device of claim 11, wherein the downlink signalquality comprises a downlink signal-to-interference-plus-noise-ratio(SINR) and the downlink signal quality threshold comprises a downlinkSINR threshold determined by the wireless communication device.
 14. Thewireless communication device of claim 11, wherein the processingcircuitry is further configured to cause the wireless communicationdevice to: measure a channel quality of the second network beforereselecting to the second network; remain on the first network when thechannel quality of the second network does not satisfy a channel qualitythreshold; and reselect to the second network when the channel qualityof the second network satisfies the channel quality threshold, thedownlink signal quality of the first network does not satisfy thedownlink signal quality threshold, and the downlink signal strength ofthe first network satisfies the downlink signal strength threshold. 15.The wireless communication device of claim 14, wherein the channelquality threshold comprises a threshold for reselection or handoverspecified by the first network and/or the second network.
 16. Thewireless communication device of claim 14, wherein the first networkcomprises an LTE wireless network and the second network comprises alegacy wireless network.
 17. A non-transitory computer-readable mediumstoring instructions that, when executed by one or more processors of awireless communication device, cause the wireless communication deviceto: measure a downlink signal strength and a downlink signal quality ofa first network to which the wireless communication device has anestablished connection; determine whether the downlink signal strengthsatisfies a downlink signal strength threshold; disconnect from thefirst network and reselect to a second network, when the downlink signalstrength threshold is not satisfied; and when the downlink signalstrength satisfies the downlink signal strength threshold: determinewhether the downlink signal quality satisfies a downlink signal qualitythreshold, and disconnect from the first network and reselect to thesecond network when the downlink signal quality does not satisfy thedownlink signal quality threshold.
 18. The non-transitorycomputer-readable medium of claim 17, wherein the instructions, whenexecuted by the one or more processors, further cause the wirelesscommunication device to: measure a channel quality of the second networkbefore reselecting to the second network; remain on the first networkwhen the channel quality of the second network does not satisfy achannel quality threshold; and reselect to the second network when thechannel quality of the second network satisfies the channel qualitythreshold, the downlink signal quality of the first network does notsatisfy the downlink signal quality threshold, and the downlink signalstrength of the first network satisfies the downlink signal strengththreshold.
 19. The non-transitory computer-readable medium of claim 17,wherein the downlink signal strength threshold is determined by thefirst network, and the downlink signal quality threshold is determinedby the wireless communication device.
 20. The non-transitorycomputer-readable medium of claim 17, wherein the first networkcomprises an LTE wireless network and the second network comprises alegacy wireless network.